In a mixing bowl,combine together crushed biscuits and butter.Blend with your fingertips until the mixture resembles coarse crumbs.Keep aside.

In a sauce pan,combine together milk,sugar,cocoa powder and cornflour.Mix well until combined.Cook this milk mixture until it turns really thick,stirring continuously.Allow it to cool completely,add vanilla and mix well.

Place a layer of the biscuit crumbs in a large serving dish,or small individual bowls.Add a layer of the prepared chocolate pudding ,repeat layers finishing off with biscuit crumbs.

Top it with whipped cream,if desired.Refrigerated for about 3 to 4 hours.Serve cold.